Choosing a display for my NP9758-S, need input: FHD vs 4k

I'm building a NP9758-S, and in choosing a display, I could really use some input. I'll be using the laptop mainly for gaming. Cost is of low priority since I've been saving up for this.

Here are my options:
1) LG LP156WF6-SPB1 (g-sync capable) Specs Here
2) Samsung LTN156FL02-101 (g-sync capable) Specs Here
3)...

Choosing a display for my NP9758-S, need input: FHD vs 4k